Re: Defaulting wal_sync_method to fdatasync on Linux for 9.1?

On Mon, Nov 8, 2010 at 01:35, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> Yes; it's supposed to, and that logic works fine on some other platforms.

No, the logic was broken to begin with. Linux technically supported
O_DSYNC all along. PostgreSQL used fdatasync as the default. Now,
because Linux added proper O_SYNC support, PostgreSQL suddenly prefers
O_DSYNC over fdatasync?

> Until you've
> quantified which of the cases do that--which is required for reliable
> operation of PostgreSQL--and which don't, you don't have any data that can
> be used to draw a conclusion from.  If some setups are faster because they
> write less reliably, that doesn't automatically make them the better choice.

I don't see your point. If fdatasync worked on Linux, AS THE DEFAULT,
all the time until recently, then how does it all of a sudden need
proof NOW?

If anything, the new open_datasync should be scrutinized because it
WASN'T the default before and it hasn't gotten as much testing on
Linux.

Regards,
Marti